Analisi di vulnerabilità sismica di edifici esistenti in c.a.: la scuola media "A. Mordini" di Barga

La presente tesi si inquadra nel macrotema della valutazione sismica di edifici esistenti in cemento armato, con particolare enfasi riguardo ai metodi di analisi dinamica lineare con spettro di risposta ridotto e analisi statica non lineare, nota anche come analisi pushover (PO), in presenza di irregolarità strutturali, soprattutto in pianta. L’analisi PO è, infatti, più affidabile per edifici, o più generalmente costruzioni, dotati di una certa regolarità per quanto riguarda le caratteristiche di rigidezza e di resistenza e in una tale ottica si inquadrano le procedure proposte nelle varie normative e linee guida, tra cui le americane (USA) e le europee; per superare questa limitazione sono state ideate e si stanno sviluppando varie metodologie, tra cui citiamo quelle di Antoniou e Pinho, Chopra e Goel e Fajfar. L’ultima metodologia citata è stata impiegata per l’analisi di un edificio scolastico esistente e per la sua valutazione sismica. Partendo dal confronto dei risultati forniti dalle analisi dinamiche lineari con spettro di risposta ridotto con quelli della PO si sono tratte delle conclusioni sulle conseguenze che l’applicazione di tali metodi ha sull’esito della valutazione suddetta

Erosion von Salzmarschrändern durch winderzeugte Wellen

Salt marsh edge erosion due to wind-waves is one of the chief mechanisms leading to marsh area reduction in various parts of the world. This entails the loss of a large amount of ecosystem services in estuarine and coastal environments. The present research seeks to improve the knowledge on the erosion of the boundaries of the salt marshes, focusing on the spatial scale of the salt marsh bank and the adjacent mudflat. The topic is addressed through three different approaches. The interpretation of laboratory experiments, previously carried out, inspired the development of a mathematical model describing the incipient mass failure of toppling type. The model is able to identify the wave group responsible for the failure of a block of soil identified by the presence of a tension crack and gives information about the combinations of water level and wave height leading to bank instability. A field campaign was carried out on a salt marsh of the lagoon of Venice. Localized and detailed measurements of erosion and wave climate allowed to determine a relationship between wave power and erosion rate at monthly time scale. Field data also demonstrated that in the monitored area the lower part of the bank is more prone to erosion than the top, leading to the formation of cantilever profiles. A simple mathematical model based on field data shows that the different erodibility of the marsh scarp along the vertical profile can lead to a higher cumulative retreat of the marsh edge. The development of a 1-D process-based model allowed to investigate, through numerical experiments, the effect of variations of soil composition on the evolution of the bank profile, with and without vegetation. A muddy bank tends to retreat by maintaining the steep profile of the cliff, whereas decreasing the mud fraction the bank attains a more gentle profile. The effect of vegetation in strengthening the soil matrix against shear erosion is negligible for muddy banks and significant for sandy banks. Independently of soil composition, vegetation makes the bank to retreat maintaining a steep profile. Present research gives several insights into the process of erosion of salt marsh edges due to the effect of wind-induced waves. Obtained results can be employed to evaluate and plan measures aimed at the preservation of salt marsh area and they also lay the base for future researches in the field of the morphodynamic evolution of tidal environments.Erosion von Salzmarschrändern durch winderzeugte Wellen ist einer der wichtigsten Mechanismen zur führenden Sumpfgebiet Reduktion in verschiedenen Teilen der Welt. Dies bringt den Verlust einer großen Menge von Ökosystemleistungen in Mündungs- und Küstengebiete. Die vorliegende Untersuchung soll das Wissen über die Erosion der Grenzen der Salzwiesen, die sich auf die räumlichen Skala der Salzsumpf Bank und dem benachbarten mudflat zu verbessern. Das Thema wird durch drei verschiedene Ansätze gerichtet. Die Interpretation von Laborexperimenten, inspiriert vorher durchgeführt, um die Entwicklung eines mathematischen Modells der Beschreibung der einsetzenden Massenausfall des Typs Umkippen. Das Modell ist in der Lage, die Wellengruppe verantwortlich für das Scheitern eines Blocks des Bodens durch das Vorhandensein eines Spannungsriss zu identifizieren und gibt Auskunft über die Kombinationen von Wasserstand und Wellenhöhe zu Bank Instabilität führt. Ein Feld Kampagne wurde auf einem Salz-Sumpf der Lagune von Venedig durchgeführt. Lokalisierte und detaillierte Messungen von Erosion und Wellenklima erlaubt eine Beziehung zwischen Wellenkraft und Erosionsrate in monatlichen Zeitskala zu bestimmen. Felddaten zeigten auch, daß in dem überwachten Bereich der untere Teil der Bank ist anfälliger für Erosion als die Spitze, was zur Bildung von Auslegerprofilen. Ein einfaches mathematisches Modell basierend auf Felddaten zeigt, dass die verschiedenen erodibility des Sumpfes Böschung entlang der vertikalen Profil auf eine höhere kumulative Rückzug des Sumpfes Kante führen kann. Die Entwicklung eines 1-D-Verfahren basierendes Modell erlaubt, durch numerische Experimente zu untersuchen, um die Wirkung von Variationen der Zusammensetzung des Bodens auf die Entwicklung des Bankprofil, mit und ohne Vegetation. Ein schlammiger Bank neigt dazu, durch die Aufrechterhaltung der steilen Profil der Klippe zum Rückzug, während die Verringerung der Schlammfraktion die Bank eine sanftere Profil erreicht. Die Wirkung der Vegetation in der Bodenmatrix gegen Scher Erosion Stärkung vernachlässigbar für schlammige Banken und bedeutsam für Sandbanken. Unabhängig von der Bodenbeschaffenheit, Vegetation macht die Bank zum Rückzug einen steilen Profil. Derzeitige Forschung gibt mehrere Einblicke in den Prozess der Erosion der Salzsumpf aufgrund der Wirkung von Wind-induzierten Wellen Kanten. Die erhaltenen Ergebnisse können bei der Erhaltung der Salzwiesenfläche zu bewerten und zu planen Maßnahmen zur eingesetzt werden, und sie legen auch die Basis für zukünftige Forschungen auf dem Gebiet der morphodynamische Entwicklung von Gezeiten Umgebungen

Optimized TiO2 blocking layers for dye-sensitized solar cells (DSSC)

In recent years much attention has been paid to dye-sensitized solar cells due to their low cost and wide applicability. The modest efficiencies achieved by these devices are caused by several phenomena including electronic losses due to parasitic electronic reactions. One of the most common way to reduce the electronic losses is to introduce a compact layer of conductive material (blocking layer) between the transparent conductive substrate and the sensitized semiconductor film. Aim of this work was to asses the correlation between the most common deposition processes and the final properties of the blocking layers produced by them. The blocking layer of TiO2 was prepared on FTO glass using two of the most commonly used colloidal deposition processes: dip and spin coating. The results obtained with the conventional dip coating were compared with the ones coming from spin coating of two different solutions of TiCl4 (50 mM). These solutions were characterized in terms of viscosity, surface tension and contact angle. The spin coating parameters were optimized on the basis of these analysis. The influence of subsequent cycles of deposition (2,4,6) was also evaluated. The TiO2 films obtained were deeply characterized (AFM, SEM, UV-vis and electrochemical measurement) in order to assess the best conditions needed to obtain an efficient blocking layer (BL)

Geopolymer oxygen carriers for chemical-looping combustion

One of the best alternatives to reduce the economic cost of CO2 capture is represented by the chemical looping combustion (CLC). This technology accomplishes indirect fuel combustion by use of a solid oxygen carrier (OC), generally a metal oxide having the capability of transporting the oxygen needed for the combustion from an air reactor to a fuel reactor, usually designed as two coupled fluidized beds. The combustion takes place in the fuel reactor through the reaction between the fuel and the solid OC, which is consequently reduced to a lower oxidation state. The reduced OC is then transferred to the air reactor, where it is regenerated by oxidation in air at high temperature. Therefore, the CLC process enables the inherent separation of the produced CO2, the stream exiting the fuel reactor being only composed of CO2 and H2O, easily separable by water condensation. Please click Additional Files below to see the full abstract

Morphological and electrochemical characterization of TiO2 blocking layers in Dye Sensitized Solar Cells

In recent years much attention has been paid to dye-sensitized solar cells due to their low cost and wide applicability. The modest efficiencies achieved by these devices are caused by several phenomena, including electronic losses due to parasitic electronic reactions. One of the most common way to reduce the electronic losses is to introduce a compact layer of conductive material (blocking layer) between the transparent conductive substrate and the sensitized semiconductor film. Aim of this work was to asses the correlation between the most common deposition processes (spin coating and dip coating) and the morphological and electrochemical properties of the blocking layers produced by them. The blocking layer of TiO2 was prepared on FTO glass, and the results obtained with the conventional dip coating were compared with the ones coming from spin coating of two different solutions of TiCl4 (50 mM). The TiO2 films obtained were deeply characterized in particular from the electrochemical point of view in order to assess the best conditions needed to obtain an efficient blocking layer. Cyclic voltammetry and electrochemical impedance spectroscopy (EIS) were used to understand the electrochemical behavior of the blocking layer (BL